This week's butterfly is unique. Originally called Papilio antenor, it was classified as an Atrophaneura for some years, then reconsidered and found to be distinctive enough to be put in its own genus, all by itself, as Pharmacophagus antenor--Antenor the Medicine Eater. The English name, Madagascar Giant, may be more descriptive. An elaborate technical discussion of the classification process is available at https://digitallibrary.amnh.org/handle/2246/911 . It's not found on most lists of the Atrophaneuras any more, but it is found on some, so I'm breaking out of alphabetical order to consider it now.
You can spot web sites that have been edited by computer because computers "correct" the species name to "anterior." This is incorrect. This butterfly was named during the years when naturalists were naming species after characters in ancient literature. Antenor, in the Iliad, was a wise counselor who advised that the king of Troy should send Helen back to her rightful husband and try to make peace with the Greeks. Like Cassandra, his wisdom was ignored. Like many characters whose names were given to the "funereal black" Atrophaneuras, he was associated with a funeral.
Photo by Hugh Lansdown at Minden Pictures.
It's a "giant" because its wingspan is typically 5 to 6 inches, easily twice the size of most North American swallowtails. The fore wings show varying amounts of white spots. The hind wings have a few white spots but are mostly dark, iridescent blue-black, with red or pink spots around the edges. The thorax is black; the head and abdomen (tail) sections are red or pink. The red color sometimes fades to orange.
Photo by TheoG, who posted it as a forum discussion apparently in Malagasy French slang (coquille for "mistake"): https://www.insecte.org/forum/viewtopic.php?t=60749
Because Madagascar is the home of so many unique lifeforms, and these butterflies seem less immediately endangered than several others, the butterflies don't seem to command as much attention as their size, if nothing else, would command in the rest of the world. They are admired by visitors to the island, often described as "magnificent." They are described as "powering along" in flight, being mistaken for birds. They are big, bold, and easily photographed; pictures are easy to find online. According to the Swallowtail and Birdwing Butterfly Trust web site, although " reasonably well known and not immediately threatened," they "require continuous monitoring...because they are found in areas where habitat destruction is accelerating." (And, perhaps, because they're pollinators of pretty flowers?)
Two British scientists published the story of their attempt to rear these butterflies in England, where the caterpillars ate the species of Aristolochia that was available. The mother butterfly produced 25 eggs in one week. She tried to separate her eggs so the caterpillars would have enough food, but placed the first two eggs on one plant, together, suggesting that separation is not as critical to survival in this species as it is in some swallowtail species, though the caterpillars did eat their shed skins. The caterpillars grew rapidly at first, but none lived to maturity. Madame Butterfly mated again, but the second mating did not produce viable eggs. Nevertheless, the scientists who made the experiment were able to publish nice clear pictures of the eggs and young caterpillars at http://www.troplep.org/TLR/9-1/pdf1.pdf .
The egg is bead-shaped, imperfectly round, dotted with droplets of aristolochic acid that discourage predators.
The caterpillar is not as dramatically humpbacked as some swallowtail caterpillars. Like many of the Atrophaneuras, it's covered in bumps and lumps that discourage birds, with a few bristles that it probably hopes will remind predators of the nasty stinging bristles of some silk moth caterpillars, and has a white "saddle" or "belt" marking and some white spots on a mostly dark body. Toxic only when eaten, it gets some survival benefit from resembling the droppings of a sick bird or animal.
Caterpillars eat a species of Aristolochia or sometimes another plant in the genus Quisqualis. All the Aristolochias are somewhat toxic to most animals, but some contain phytochemicals that humans have used as medicines--hence Pharmacophagus, medicine eater.
The chrysalis has the dead-leaf look typical of several swallowtails but, while occupied, it's more colorful, suggesting a slowly dying tropical leaf rather than a crumbling one:
Photo donated to Wikipedia By Charles J. Sharp - Own work, from Sharp Photography, sharpphotography.co.uk, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=76393607
After the butterfly leaves, however, the empty shell of the chrysalis looks similar to other abandoned Atrophaneura chrysalides. The color of the pupa comes from the living animal inside.
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